The invention relates to a bridge or gantry crane having a crane trolley which can be moved along a crane carrier in the trolley travel direction and which supports at least one mast which can be moved in a vertical raising and lowering direction and on which a load-receiving means for containers is suspended and, in particular, to such a bridge or gantry crane for handling ISO containers.
European patent EP 1 365 984 B1 discloses a bridge or gantry crane for stacking containers, in particular ISO containers, which, within a container terminal, places containers into storage in a storage area or removes them from storage therein. Within the storage area the containers are set down on a rectangular store floor in rows and columns and up to four containers are stacked one on top of another. Within the storage area the set-down containers have their longitudinal extension aligned with the longitudinal direction of the storage area and, for example, ten containers are set down next to each other across the width of the storage area and narrowly spaced apart from each other. The bridge or gantry crane has a crane carrier which substantially spans the cuboidal storage area widthwise, on which the crane carrier and in the longitudinal direction thereof a crane trolley can travel. When the bridge or gantry crane is formed as a bridge crane, the crane carrier has, on each of its opposite ends, at least one running gear, by means of which the crane carrier can travel along rails. In accordance with the construction of a bridge crane the rails are elevated for this purpose by means of vertical supports which are disposed laterally next to the storage area and are anchored in the floor. The bridge crane is therefore able to travel in the longitudinal direction of the storage area by means of the running gears of the crane carrier and is able to travel transverse thereto by means of the crane trolley which can travel on the crane carrier. When the bridge or gantry crane is formed as a gantry crane, the rails for the crane carrier are disposed on the floor laterally adjoining the storage area and the running gears of the crane carrier are connected to the ends of the crane carrier via vertical supports.
In order to be able to handle the containers by means of the crane trolley, the crane trolley is provided with a mast which can be raised or lowered and is guided in the vertical direction. The mast is formed as a box girder and hoisting mechanisms are arranged on the crane trolley for the raising and lowering movement of the mast. A load-receiving means for containers, in particular a so-called spreader, is suspended on the lower end of the mast which is oriented in the direction of the containers to be handled. The use of a rigid mast between the crane trolley and the load-receiving means makes it possible to handle the containers with a low level of swinging in contrast to load-receiving means which are also used suspended on cables.
European patent application EP 1 939 131 A2 discloses a container bridge with a crane trolley, which crane trolley has two cable-winding mechanisms one behind the other when seen in the trolley travel direction, on which cable-winding mechanisms a twin load-receiving means for two ISO containers is suspended by hoisting cables. The individual load-receiving means, however, are connected to each other via hydraulic cylinders, which are oriented substantially horizontally and in the trolley travel direction, in order to be able to adjust the spacing between the individual load-receiving means. In a corresponding manner, the load-receiving means cannot be moved independently of each other in the hoisting and steering direction.
Furthermore, the patent document U.S. Pat. No. 5,718,550 A discloses a gantry crane for handling containers, which in a conventional manner has a horizontal crane carrier which carries a first crane trolley and a second crane trolley in front of, or behind, it as seen in the trolley travel direction. Each of the two crane trolleys has a hoisting mechanism on which a spreader frame is attached via cables in order to receive the containers to be handled. These spreader frames are formed in such a way that they can transport two or three containers at the same time in order thereby to increase the handling capacity. The first crane trolley and the second crane trolley each therefore support only a single load-receiving means, which is suspended via cables on a single hoisting mechanism, and are able to travel along the crane carrier independently of each other.